Extensive research through the University of Western Australia has shown the machine kills 95 per cent of the weed seeds collected in the chaff.

According to the Grains Research and Development Corporation (GRDC), weeds cost Australian grain farmers around $3.5 billion a year, and there is an increasing problem with weeds such as annual ryegrass that have built up a resistance to commonly used herbicides.

"Five to seven years ago, particularly in places like the Western Australian Wheatbelt, there was quite a strong feeling that herbicide resistance was going to cause people to have to walk off their farms," said GRDC managing director Steve Jefferies.

'Most elegant' invention targets root of the problem

Mr Harrington grows barley, wheat and other grains on his property near Darkan, about 200 kilometres south of Perth.

An innovator by nature, more than a decade ago he realised if he did not do something about weed seeds at harvest, he "would fail like [his] Wheatbelt cousins" — so he looked at ways of crushing the weed seeds that were collected up in the chaff when the grain crops were harvested.

"I was going to catch it, cart it off, cook it or crush it," he said.

Mr Harrington originally developed a machine that would be towed behind a header, but he realised that would not suit most farmers, so with input from University of South Australia's engineering researchers and funds through the GRDC, a model was developed that could be integrated into harvesters.

The HSD system is based around the cage mill as the chaff processing unit. A pneumatic chaff delivery system, incorporating a cross auger and blower fan, collects and delivers the chaff that is pushed out the rear of the harvester and pushes that material, which is full of weed seeds, through the centre of the cage mill.

The weed seeds are smashed into a fine powder by rotating metal blades, and the inert powder is spread immediately back on the paddock.

Director of the Australian Herbicide Resistance Initiative (AHRI) Stephen Powles said the HSD was "the most elegant tool" in a system called harvest weed seed control — a process of managing weeds at harvest time, rather than relying on herbicides to knock weeds down during the growing season.

"I think we should all be proud of it," Professor Powles said of the HSD invention.

"[Ray Harrington] … is a great Australian, he is a great innovator, a great farmer and an outstanding inventor."

Mr Wheatley said the company was manufacturing around 12 to 15 machines a month, and they retailed fully installed for $160,000.

Most of the machines have been sold to Western Australian farmers, but several have also been sent to South Australia's Eyre Peninsula, and testing stands have been exported to the United States, Canada and South America.

"There's a huge amount of interest [in the HSD] in the US market, where they have a number of major weed issues — particularly with Palmer Amaranth," Mr Wheatley said.

Mr Harrington said he did not expect to become "very rich" from his invention, but that he would like to retire "in comfort" before handing over the farm to the next generation.

"It's been a labour of love for 14 years," Mr Harrington said.

"I am so pleased it has come to fruit, because it could have failed. I know if we adopt weed seed management across the globe, we are going to have a chance."